Negotiations between two parties are becoming complex, so party buyer makes some notes that both parties sign. However, when the work is being done, party seller claims that they are not required to provide an item they both agreed to during negotiations, because it was not included in the subsequent contract, in this case, party seller is:
A、Generally correct because both parties are only required to perform what is in the contract
B、Generally incorrect because all agreements must be upheld
C、Incorrect because both parties must comply with what they agreed upon
D、Correct because both parties must comply with what they agreed to in the signed contract